Zoonoses in Livestock in Kenya – The Beginnings of Surveillance

By Steven Kemp, PhD student, University of Liverpool

After a period of intense lab work at both KEMRI and the UK, investigating the patterns of antimicrobial resistance in faecal bacteria isolated from slaughterhouse workers in Busia County and the surrounding areas, I have returned to Kenya to begin the next phase of my PhD project.

ZooLinK is a cyclical programme which aims to set up surveillance systems of both human and animal health sectors over a long period of time. Surveillance of disease is particularly important, as the more information we have, the better we can treat diseases in both human and animal sectors. Recent research by colleagues indicates that the incidence of several zoonotic diseases, including E. coli, Salmonella sp. and others are vastly underestimated.

In recent times, we often hear about how we should now look to conform to the ‘One Health’ approach; this is where, in order to combat issues surrounding antimicrobial resistance and associated issues effectively, intersectoral approaches which share the cost and responsibility evenly between environmental, human & veterinary health professionals is required. In theory, this would be a perfect way to help educate and better promote antimicrobial stewardship.

Currently, I have large amounts of data on access to, use of, and perceptions of antimicrobials from a variety of parties, including animal healthcare workers, district veterinary offices, farmers and agrovet shops. Over the last three months, I have added to this repository by investigating the amounts of antibiotic resistance found in E. coli, which have been isolated from the faeces of workers in 142 slaughterhouses which were selected in western Kenya. These included slaughterhouses in Busia County and the surrounding Kakamega and Bungoma counties.

For the next portion of this study, I am attempting to collect four different sets of samples – to complete the ‘picture’. I will attempt to collect both human and animal faecal samples, from farmers and farm animals, water samples (to determine if there are patterns of resistance in animals which share common grazing grounds) and environmental samples (from the inside of homesteads, where animals are allowed to roam). By covering all of these bases, we will be able to eventually determine not only if there is transfer of antimicrobial resistance between animals and humans and the environment, but also which direction it is going in.

Typical small-holder farm in Funyula, Busia. Most farmers manage between 5-25 cattle.

Example of environment which may also be a good idea to sample in the future. If antimicrobial resistance can be found in the envi-ronment, then why not in wild animals such as these Zebra?

Antigenic diversity in the African trypanosomes Trypanosoma congolense and Trypanosoma vivax

Blog entry authored by Sara Silva Pereira, PhD student University of Liverpool.

Trypanosomes are extracellular blood parasites, transmitted by the bite of tsetse flies and cause nagana, a wasting disease severely compromising both animal health and livestock productivity in Sub-Saharan Africa. Nagana remains a challenge mainly due to the process of antigenic variation, employed by the para-site for immune evasion.

Blood sampling

I came to Busia to conduct a longitudinal experiment on natural cattle infections of T. congolense to better understand the process of antigenic switching. With the help of a local veterinary surgeon, we screened cattle across for trypanosomes using thin blood smears and high centrifugation technique and followed the infection in positive animals for a month, after which the animals were treated.

The collected materials will be subject to DNA and RNA sequencing and Mass Spectometry to characterise the genetic repertoire of the parasites and the antigens expressed over time.

Challenges associated with tracking the movements of people and their livestock

Phase two of this study (detailed in the previous ZooLink newsletter) began in November. Over the last two months, we revisited 27 households that we collected GPS data from in phase one in order to track the movements of the same people and livestock as we did in July and August of this year. Briefly, this involves visiting randomly selected households in Busia County and asking the participant to wear a small GPS tracker on a lanyard around their neck or alternatively, to keep it in a pocket on their person for one week. During the same visits, we also attach an identical GPS unit on a collar to one of the livestock belonging to the household. After the week is over we return to the household to collect the trackers and to ask a few questions about the experience.

Cattle with trackers around their necks

Although most people have been keen to participate in the study for a second time, we often hear of challenges they encountered while wearing the trackers. These are nearly always due to other people’s perceptions of the purpose of the trackers and the research. For example, many participants reported that they were questioned by people from other households, which led to participants having to convince other people of the purpose and worth of the study. In the worst cases, participants reported that other people were convinced that the tracker was listening to their conversations, was a bomb or was doing “the work of the devil”. However, it was heartening to hear that in all cases the participant attempted to explain the study to other people, with varying results. Interestingly, the intensity of the questioning by outsiders seemed to be related to the participant’s age and gender: We tended to find that young women wearing the trackers were more likely to be subjected to questioning and (attempted) persuasion to discontinue their participation in the study than others. Nonetheless, participants invariably reported that while others might be doubtful, they themselves remained convinced of the purpose of the study and continued to wear the trackers.

Cattle outside a “boma” with trackers around their necks

Sometimes it was difficult to find our participants and collect the trackers when the week was up – we would drive to a sub-location up to two hours away from Busia town, only to find that the people we wanted to visit were out and we would have to track them down, mainly by asking the villagers where our participants might be. On the bright side, this also meant that our trackers were out collecting interesting data, and has led to us stumbling upon various events within the villages, including a funeral, a circumcision ceremony and a fishing trip.

Overall, this second phase of fieldwork has been largely successful!

This blog article was authored by Jessica Floyd, PhD student, University of Southampton and also appears in our Zoolink Newsletter Volume1 Issue 2

Do livestock have a role in the emergence of disease in urban cities?

One of the primary objectives of the Urban Zoo project is to quantify and understand microbial diversity in an urban setting and to try and link that to urban livestock keeping. In so doing we aim to elucidate the possible role of livestock as a risk factor in the emergence of disease in cities.

To give us a handle on microbial diversity we have chosen commensal Escherichia coli as an indicator species, which we have isolated from samples taken from a diversity of sources across the city of Nairobi. These comprise people and their living spaces, including the food they eat; their immediate environments, including water sources, waste and wildlife; and the livestock that they keep either for their own consumption or for sale. From these samples we isolate and culture E. coli, extract their DNA, and perform whole genome sequencing, enabling us to compare isolates from different compartments and to determine how closely related they are, and thus how microorganisms might pass from one to another.

The collection of these samples has been guided by a highly structured sampling frame, which I described in Urban Zoo newsletter number 7. Essentially, we have selected 33 sub-locations in Nairobi representing a range of social strata and, within each, have chosen 3 households to sample: one with no livestock; one with only monogastric species (pigs or chickens); and one with ruminant livestock (sheep, goats or cattle); You can view the spatial maps at our earlier post by clicking here .

The collection of such comprehensive data from these 99 households was an enormous undertaking and has been a considerable logistical feat of coordination between the field and the laboratory. The good news is that the sampling is now complete, thanks to the heroic efforts of the field team, led by Judy Bettridge and James Akoko, and of our colleagues in the laboratories.

Overall, 2,351 samples have been collected and we managed to culture E. coli from 80% of these (1,850). Once the last few have been done this will give us 1,809 whole genome sequences to analyse. 327 of these are from people; 58 from the places where they prepare food; 64 from animal source foods (milk meat and eggs); 644 from 12 different species of livestock; 239 from the environment around the home-stead including water sources; and 477 from a wide diversity of wildlife in the vicinity of the household.

But it is not over yet. We will very soon have finalised the sequencing and now comes the equally challenging task of deciphering all of this genetic data to unveil the pattern of microbial diversity across Nairobi. Over to you Melissa!

On that note, I would like once again to congratulate the field and laboratory teams, and to wish everyone a great year ahead, 2017.

This article was authored by Dr. Timothy Robinson who is a co-principal investigator in the Urban Zoo project and also a principal scientist with ILRI’s Livestock Systems and Environment research group.

Non-typhoidal Salmonella (NTS) in pigs in Busia, Nairobi and Malawi

This blog post was authored by Catherine Wilson an MRES Student from the University of Liverpool attached under our #ZooLink project

I am investigating the prevalence of Non-typhoidal Salmonella (NTS) in pigs in both Kenya and Malawi in extensive, low input production systems.  The aim is to determine whether invasive NTS are present in the pig population of three study areas; one rural and one urban area in Kenya and one rural region of Malawi. In sub-Saharan Africa, NTS is a leading cause of human mortality, particularly in the very young, old, malnourished, or those suffering from co-morbidities such as HIV or malaria.

Pig slaughter slab in Bumala

Pig slaughter slab in Bumala

An invasive NTS serovar has been found to be able to cause severe disease in chickens; suspicion is therefore arising that transmission between humans is not the sole route of spread of NTS, and that zoonotic transmission, especially from pigs, may have a role to play in the epidemiology of the disease. Should this invasive strain of bacteria be found in pigs, we will assess whether the same serovar clinically affects humans in the same geographical location, using data already gathered from human hospitals. A correlation between the two would indicate that zoonotic transmission may be occurring.

The final part of this study will assess the presence of drug resistance in the strains of NTS isolated from pigs, and whether this bears any correlation to a similar antimicrobial resistance pattern of NTS to that previously detected in humans in the same area.  Should antimicrobial resistance be detected, other management techniques for the swine, such alterations in husbandry and hygiene, may be trialed.  In the longer-term vaccination development may be a possibility as an important method of preventing zoonotic disease transmission in the study areas, for which research is currently in the very early stages.

For sampling,  both faecal and mesenteric lymph nodes samples were collected post mortem from 256 pigs in Busia and 304 pigs in Nairobi.  The location in which the pigs were reared, as well as details of signalment, any previous antibiotic treatment if known and the method of transport of the pig to the slaughterhouse, were recorded for each individual pig.

Samples were processed at the Busia Field Lab and ILRI laboratories respectively. Culture and serotyping was carried out to confirm the presence of Salmonella followed by antimicrobial susceptibility testing to a range of antibiotics.  Positive isolates have then been stored for transport to the UK, where whole genome sequencing will be undertaken to identify the presence of any antimicrobial resistance genes. Once the results have returned, analysis is planned compare antimicrobial resistance profiles of the pig samples to those of humans in the same geographical location, to assess whether zoonotic transmission may be occurring.

Pin It on Pinterest